King Charles cancels engagements after experiencing temporary side effects of cancer treatment

(CNN) — Britain’s King Charles “required a short period of observation in hospital” on Thursday after experiencing “temporary side effects” from a scheduled cancer treatment in the morning, Buckingham Palace has said.

Charles, 76, has now returned to Clarence House and, on medical advice, has canceled his engagements on Friday, the palace said in a statement.

“His Majesty would like to send his apologies to all those who may be inconvenienced or disappointed as a result,” it added.

The King was set to receive credentials from the ambassadors of three countries on Thursday, and was scheduled to undertake four public engagements in Birmingham, central England, on Friday.

“He very much hopes that they can be rescheduled in due course and offers his deepest apologies to all those who had worked so hard to make the planned visit possible,” a Buckingham Palace spokesperson said.

A royal source described it as “the most minor bump in the road that’s very much heading in the right direction.”

The statement from the palace came late on Thursday to allow the King some time to consult with his staff and medical team once he had returned home to Clarence House over whether he should continue Friday’s events.

Charles was said to be in good form after the treatment, continuing to work on state papers and make phone calls from his study, a royal source told CNN.

He and Queen Camilla are still expected to travel to Italy for a state visit in April. The four-day trip was also supposed to include a visit to the Vatican, but earlier this week the King and Queen postponed their state visit to the Holy See as Pope Francis recuperates from his recent case of double pneumonia.

The King’s recovery is continuing to proceed in a positive direction and the unspecified side effects he experienced on Thursday are temporary and not uncommon with many medical treatments, the royal source said.

A spokesperson for UK Prime Minister Keir Starmer said he “wishes His Majesty the King all the very best,” according to Britain’s PA Media news agency.

Queen Camilla did not accompany Charles for the brief visit to the London Clinic, the same private hospital near Regent’s Park where he underwent a procedure for an enlarged prostate in January 2024. The King revealed his cancer diagnosis a month later.

He briefly stepped away from public-facing duties while he received treatment for the undisclosed form of cancer, returning to them a few months later in April 2024. In his first official engagement following his diagnosis, Charles visited a cancer treatment center, where he leaned on his own personal experience when talking to medical teams as well as while connecting with patients and their families.

Thousands of people sent the King messages of support when he was first diagnosed, which he said “reduced me to tears,” according to a statement released by the palace at the time. “Such kind thoughts are the greatest comfort and encouragement,” Charles said.

Since Charles’ diagnosis, it’s understood that his diary has been developed in full consultation with his medical team to protect and prioritize his recovery.

Charles is said to have found carrying out state business and daily engagements in recent months of great benefit to his overall wellbeing. After wrapping up his trip to Australia and Samoa last fall, a palace official said at the time that the visit had lifted “his spirits, his mood and his recovery,” according to PA, and described it as a “perfect tonic.”

Earlier this week, he hosted a reception for regional media at Buckingham Palace and an investiture at Windsor Castle, while last week saw him carry out a three-day trip to Northern Ireland.

This story has been updated with developments.

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